Method and apparatus for clockless conversion of portion of electric charge to digital word

ABSTRACT

Method and apparatus for accumulation of electric charge delivered to the charge input (InQ) in the sampling capacitor (C n ) and in realization of the process of charge redistribution in the array of redistribution (A) by changing states of signals from relevant control outputs and in assignment of relevant values to bits in the digital word by means of the control module (CM). Method is characterized in that after detection of the beginning of the next gate signal (G x+1 ), the charge is accumulated in the additional sampling capacitor (C nA ), and then the process of charge redistribution is realized and relevant values are assigned to bits of the digital word. When the beginning of the subsequent gate signal (G x+2 ) is detected, the next cycle begins and electric charge is accumulated in the sampling capacitor (C n ) again.

This application claims priority to Polish patent application number P 397 953, filed Jan. 31, 2012, and Polish patent application number P 397 954, filed Jan. 31, 2012, the contents of which are incorporated herein by reference.

The subject of this invention is a method and an apparatus for clockless conversion of a portion of electric charge to a digital word that can be applied in monitoring and control systems.

The method for the conversion of a portion of electric charge to a digital word known from the Polish patent application P-391419 (PCT/PL2011/050020, published as PCT/PL2011/152743) consists in accumulation of electric charge in the sampling capacitor while charge is delivered to the charge input. The charge is accumulated during the active state of the gate signal.

After terminating of accumulation of electric charge in the sampling capacitor, the accumulated electric charge is submitted to the process of redistribution by deploying the charge in the array of capacitors while a capacitance value of each capacitor of a given index is twice as high as a capacitance value of a capacitor of the previous index. During the process of redistribution, the accumulated electric charge is deployed in the capacitors in the array in a way that the obtained voltage equals zero or equals the reference voltage on each capacitor or on each capacitor with the possible exception of one of capacitors. The course of the process of redistribution is controlled by means of the control module on the basis of output signals of the first and of the second comparator. Electric charge is transferred between capacitors during the process of its redistribution by the use of the current source. By means of the control module, the value one is assigned to these bits in the digital word that correspond to capacitors on which voltage equal to the reference voltage value has been obtained and the value zero is assigned to the other bits in the digital word. In one of variants of this solution, electric charge is accumulated simultaneously in the sampling capacitor and in the capacitor of the highest capacitance value in the array of capacitors which is connected to the sampling capacitor in parallel.

The apparatus the conversion of a portion of electric charge to a digital word is also known from the Polish patent application P-391419 (PCT/PL2011/050020). This apparatus comprises the array of capacitors whose control inputs are connected to the set of control outputs of the control module. The control module is equipped with the digital output, the complete conversion signal output, the gate signal input and two control inputs. The first control input of the control module is connected to the output of the first comparator whose inputs are connected to one pair of outputs of the array of capacitors. The other control input of the control module is connected to the output of the second comparator whose inputs are connected to the other pair of outputs of the array. Furthermore, the charge input, the source of auxiliary voltage together with the source of the reference voltage, the sampling capacitor and the controlled current source are connected to the array of capacitors, and the control input of the current source is connected to the relevant control output of the control module. The array of capacitors comprises on-off switches, change-over switches and the array of capacitors whose number equals the number of bits in the digital word and a capacitance value of a capacitor of a given index is twice as high as a capacitance value of a capacitor of the previous index. The top plate of the sampling capacitor and the top plate of each capacitor in the array of capacitors are connected through the first on-off switch to the first rail and/or through the second on-off switch to the second rail and the bottom plate is connected through a change-over switch to ground of a circuit or to the source of auxiliary voltage. The first rail is connected to ground of the circuit through the first rail on-off switch and to the non-inverting input of the second comparator whose inverting input is connected to the source of the reference voltage. The second rail is connected to the inverting input of the first comparator whose non-inverting input is connected to the source of auxiliary voltage. The control inputs of the first on-off switches and the control inputs of the change-over switches in the array of capacitors are coupled together and connected appropriately to the control outputs of the control module while the control inputs of the second on-off switches.

The charge input is connected to the first rail through the input on-off switch whose control input is connected to the control output of the control module. Furthermore, one end of the current source is connected to the second rail, and the other end of the current source is connected to the first rail.

In one of variants of the abovementioned apparatus, the sampling capacitor whose capacitance value is not smaller than the capacitance value of the capacitor having the highest capacitance value in the array of capacitors is connected in parallel to the capacitor of the highest capacitance value in the array of capacitors. The conversion of a portion of electric charge to the digital word is realized by changing states of signals from the relevant control outputs by means of the control module.

According to the invention, the method for clockless conversion of a portion of electric charge to a digital word consists in accumulation of electric charge delivered to the charge input in the sampling capacitor, or in the sampling capacitor and in the capacitor of the highest capacitance value in the array of redistribution, which is connected in parallel to the sampling capacitor. The charge is accumulated from the instant when the control module detects the beginning of the gate signal to the instant when the control module detects the end of the gate signal.

Then, the process of redistribution of the accumulated electric charge is realized in the array of redistribution in a known way by changing states of signals from the relevant control outputs by the use of the control module and the relevant values are assigned to bits in the digital word by means of the control module. The array of redistribution comprises the set of on-off switches, change-over switches and capacitors while a capacitance value of each capacitor of a given index is twice as high as a capacitance value of a capacitor of the previous index.

The essence of the method, according to the invention, consists in that as soon as accumulation of electric charge is terminated in the sampling capacitor, or in the sampling capacitor and in the capacitor of the highest capacitance value in the array of redistribution, which is connected to the sampling capacitor in parallel, and as soon as the beginning of the next gate signal is detected by means of the control module, electric charge delivered to the charge input is accumulated in an additional sampling capacitor. Next the process of redistribution of electric charge accumulated in the additional sampling capacitor is realized and the relevant values are assigned to bits in the digital word by means of the control module. The accumulation of electric charge in the additional sampling capacitor, the process of redistribution of electric charge accumulated in the additional sampling capacitor and assignment of the relevant values to bits in the digital word by means of the control module are realized as for the sampling capacitor.

In this method, it is possible that as soon as the accumulation of electric charge is terminated in the additional sampling capacitor and as soon as the beginning of the next gate signal is detected by means of the control module, the next cycle begins and electric charge delivered to the charge input is accumulated again in the additional sampling capacitor, or in the sampling capacitor and in the capacitor of the highest capacitance value in the array of redistribution, which is connected to the sampling capacitor in parallel.

In this method, it is possible that in a period of time when electric charge delivered to the charge input is accumulated in the additional sampling capacitor, a part of delivered charge is accumulated in the additional capacitor having the highest capacitance value in the array of redistribution which is connected to the additional sampling capacitor in parallel. A capacitance value of the additional capacitor having the highest capacitance value in the array of redistribution equals the capacitance value of the capacitor having the highest capacitance value in the array of redistribution.

In this method it is also possible that as soon as the process of redistribution is terminated, the portion of electric charge, accumulated in the last of capacitors on which reference voltage had not been reached when the process of redistribution was realized, is conserved. This portion of electric charge is taken into account when the next process of redistribution is realized.

The apparatus, according to the invention, comprises the array of redistribution whose control inputs are connected to control outputs of the control module. The control module is equipped with the digital output, the complete conversion signal output, the gate signal input, the first control input which is connected to the output of the first comparator and the other control input which is connected to the output of the second comparator. The source of auxiliary voltage, the section of the sampling capacitor and the controlled current source whose control input is connected to the relevant output controlling current source are connected to the array of redistribution. The first end of the current source is connected to the source rail and the other end of the current source is connected to the destination rail. The array of redistribution comprises the sections whose number equals the number of bits in the digital word. The section of the sampling capacitor and each section of the array of redistribution comprises the source on-off switch, the destination on-off switch, the ground change-over switch and at least one capacitor. The top plate of the sampling capacitor and the top plate of each capacitor in the array of redistribution is connected through the source on-off switch to the source rail and/or through the destination on-off switch to the destination rail and the bottom plate is connected through the ground change-over switch to ground of the circuit or to the source of auxiliary voltage. In the array of redistribution, a capacitance value of each capacitor of a given index is twice as high as a capacitance value of a capacitor of the previous index. The destination rail is connected through the destination rail on-off switch to ground of the circuit and is also connected to the non-inverting input of the second comparator whose inverting input is connected to the source of the reference voltage. The source rail is connected to the inverting input of the first comparator whose non-inverting input is connected to the source of auxiliary voltage. The control inputs of the source on-off switches and the control input of the destination rail on-off switch are connected appropriately to control outputs of the control module. The control inputs of destination on-off switches and the control inputs of the ground change-over switches are coupled together and connected appropriately to the control outputs of the control module.

A significant innovation of the apparatus is that the section of the sampling capacitor comprises the additional sampling capacitor, the top plate change-over switches and the bottom plate change-over switches and the input on-off switch connected to the charge input. The control input of the input on-off switch is connected to the output controlling the input on-off switch. The top plate of the sampling capacitor and the top plate of the additional sampling capacitor are connected to the source on-off switch and to the destination on-off switch or to the input on-off switch through the top plate change-over switches. The bottom plate of the sampling capacitor and the bottom plate of the additional sampling capacitor are connected to the ground change-over switch or to ground of the circuit by the bottom plate change-over switches. The control inputs of the top plate change-over switches and the control inputs of the bottom plate change-over switches are coupled together and connected to the output controlling change-over switches of the plates.

It is advantageous if at least one section of the array of redistribution comprises the additional capacitor and the top plate change-over switches and the bottom plate change-over switches. The top plate of the capacitor and the top plates of the additional capacitor of such section are connected to the source on-off switch and to the destination on-off switch or to an input on-off switch through the top plate change-over switches. The bottom plate of the capacitor and the bottom plate of the additional capacitor of such section are connected to the ground change-over switch or to ground of the circuit through the bottom plate change-over switches. The control inputs of the change-over top plate switches and the control inputs of bottom plate change-over switches are coupled together and connected to the output controlling change-over switches of the plates.

It is advantageous if the capacitance values of the sampling capacitor and of the additional sampling capacitor are not smaller than the capacitance value of the capacitor having the highest capacitance value in the array of redistribution.

It is also advantageous if the capacitance value of the additional capacitor in the array of redistribution equals appropriately the capacitance value of the capacitor in the array of redistribution.

Due to accumulation of the other portion of electric charge in an additional sampling capacitor, the conversion of two portions of electric charge accumulated during the duration of two successive gate signals to the digital word is possible without the need to introduce a break needed to realize the process of redistribution of the accumulated electric charge and to realize the relaxation phase. Accumulation of the other portion of electric charge in an additional sampling capacitor is realized simultaneously with realization of the process of redistribution of the first portion of electric charge in the sampling capacitor.

In this way, the results of each conversion are presented with minimal delay equal to the time of realization of the process of charge redistribution. Moreover, the realization of actions related to the conversions of both charge portions by the same control module, by the array of redistribution, by the set of comparators and by the set of current sources contributes to a reduction of amount of energy consumed per single conversion by the apparatus and in this way increases energy efficiency of its operation.

A start of a new conversion cycle after detecting the end of the actual gate signal and the beginning of the next gate signal enables the conversion of two successive charge portions by means of a single apparatus.

A use of a parallel connection of the additional capacitor having the highest capacitance value in the array of redistribution to the additional sampling capacitor allows the required capacitance value of the sampling capacitor to be reduced twice and enables a significant reduction of area occupied by a converter produced in a form of the monolithic integrated circuit. Due to a parallel connection of the additional sampling capacitor to the additional capacitor having the highest capacitance value in the array of redistribution, the maximum voltage value created on the additional sampling capacitor having the reduced capacitance value is not increased. Furthermore the time of realization of redistribution of charge, accumulated in the additional sampling capacitor and in the additional capacitor having the highest capacitance value in the array of redistribution connected to the additional sampling capacitor in parallel, is smaller at least by 25%.

Conserving in the apparatus a small portion of charge which has not been taken into consideration in the value of a digital word is also an advantage. The inclusion of the abovementioned portion of charge during the process of redistribution of the subsequent accumulated charge portion together with elimination of the need to introduce breaks between consecutive conversions causes that the sum of digital words representing a sequence of converted time intervals with the resolution defined by the quantization error.

The subject of the invention is explained in the exemplary realizations by means of figures where the apparatus is shown at different phases of conversion process represented by different states of on-off switches and change-over switches:

FIG. 1 illustrates the schematic diagram of the apparatus in the phase of relaxation before the beginning of the first conversion process.

FIG. 2 illustrates the schematic diagram of the apparatus during accumulation of electric charge in the sampling capacitor C_(n).

FIG. 3 illustrates exemplary sequence of gate signals.

FIG. 4 illustrates exemplary sequence of gate signals which occur immediately after themselves.

FIG. 5 illustrates the schematic diagram at the beginning of redistribution of charge accumulated in the sampling capacitor C_(n).

FIG. 6 illustrates the schematic diagram at the beginning of redistribution of charge accumulated in the sampling capacitor C_(n) and simultaneous accumulation of charge in the additional sampling capacitor C_(nA).

FIG. 7 illustrates the schematic diagram of the apparatus during the charge transfer from the source capacitor C_(i) to the destination capacitor C_(k) and simultaneous accumulation of charge in the additional sampling capacitor C_(nA).

FIG. 8 illustrates the schematic diagram of the other version of apparatus in a relaxation phase before the beginning of the first conversion process.

FIG. 9 illustrates the schematic diagram of the other version of apparatus during accumulation of charge in the sampling capacitor C_(n) and in the capacitor C_(n-1) which is connected to the sampling capacitor C_(n) in parallel.

According to the invention, the method for the clockless conversion of a charge portion to a digital word consists in accumulation of electric charge delivered to the charge input InQ in the sampling capacitor C_(n). The charge is accumulated from the instant when the control module CM detects the beginning of the gate signal G_(x) to the instant when the control module detects the end of the gate signal G_(x).

Then, the process of redistribution of the accumulated charge is realized in the array of redistribution A by means of the control module CM by changing the states of the signals from the relevant control outputs and the relevant values are assigned to the bits b_(n-1), b_(n-2), . . . , b₁, b₀ in digital word by means of the control module CM. The array of redistribution A comprises the set of on-off switches, the set of change-over switches and the set of capacitors while a capacitance value of a capacitor of a given index is twice as high as a capacitance value of a capacitor of the previous index. As soon as accumulation of charge in the sampling capacitor C_(n) is terminated and when the beginning of next gate signal G_(x+1) is detected by means of the control module CM, the charge delivered to the charge input InQ is accumulated in the additional sampling capacitor C_(nA). Next, the process of redistribution of charge accumulated in the additional sampling capacitor C_(nA) is realized and the relevant values are assigned to the bits b_(n-1), b_(n-2), . . . , b₁, b₀ in the digital word by means of the control module CM. The accumulation of charge in the additional sampling capacitor C_(nA), the process of redistribution of charge accumulated in the additional sampling capacitor C_(nA) and the assignment of relevant values to the bits b_(n-1), b_(n-2), . . . , b₁, b₀ in the digital word are realized in the same way as for the sampling capacitor C_(n).

The another exemplary solution is characterized in that as soon as accumulation of electric charge in the additional sampling capacitor C_(nA) is terminated and when the beginning of the subsequent gate signal G_(x+2) is detected by means of the control module CM, the next cycle begins and the charge delivered to the charge input InQ is accumulated in the sampling capacitor C_(n) again.

The another exemplary solution is characterized in that during the next gate signal G_(x+1) when the charge delivered to the charge input InQ is accumulated in the additional sampling capacitor C_(nA), a part of the delivered charge is accumulated simultaneously in the additional capacitor C_(n-1A) having the highest capacitance value in the array of redistribution which is connected to the additional sampling capacitor C_(nA) in parallel. The capacitance value of the additional capacitor C_(n-1A) having the highest capacitance value in the array of redistribution is equal to the capacitance value of the capacitor C_(n-1) having the highest capacitance value in the array of redistribution.

The another exemplary solution is characterized in that as soon as the process of redistribution is terminated in the last of capacitors on which reference voltage U_(L) had not been reached when the process of redistribution is realized, the charge accumulated in the last of capacitors is conserved.

In detail, the abovementioned process of redistribution in the exemplary solution is presented as follows.

As soon as accumulation of electric charge in the sampling capacitor C_(n) is terminated, the function of the source capacitor C_(i), whose index is defined by the content of the source index register, is assigned by means of the control module CM to the sampling capacitor C_(n) by writing the value of the index of the sampling capacitor C_(n) to this register. Simultaneously, the function of the destination capacitor C_(k), whose index is defined by the content of the destination index register, is assigned by means of the control module CM to the capacitor C_(n-1) having the highest capacitance value in the array of redistribution by writing the value of the index of the capacitor C_(n-1) to this register. Then, the process of redistribution of the accumulated charge is realized by transfer of the charge from the source capacitor C_(i) to the destination capacitor C_(k) by the use of the current source J. At the same time, the voltage U_(k) increasing on the destination capacitor C_(k) is compared to the reference voltage U_(L) by the use of the second comparator K2, and also the voltage U_(i) on the source capacitor C_(i) is observed by the use of the first comparator K1.

When the voltage U_(i) on the source capacitor C_(i) observed by the use of the first comparator K1 equals zero during the charge transfer, the function of the source capacitor C_(i) is assigned to the current destination capacitor C_(k) by means of the control module CM on the basis of the output signal of the first comparator K1 by writing the current content of the destination index register to the source index register, and the function of the destination capacitor C_(k) is assigned to the subsequent capacitor in the array of redistribution A whose capacitance value is twice lower than the capacitance value of the capacitor that acted as the destination capacitor directly before by reducing the content of the destination index register by one, and the charge transfer from a new source capacitor C_(i) to a new destination capacitor C_(k) is continued by the use of the current source J.

When the voltage U_(k) on the destination capacitor C_(k) observed by the use of the second comparator K2 equals the reference voltage U_(L) during the transfer of charge from the source capacitor C_(i) to the destination capacitor C_(k), the function of the destination capacitor C_(k) is assigned by means of the control module CM on the basis of the output signal of the second comparator K2 to the subsequent capacitor in the array of redistribution A whose capacitance value is twice lower than the capacitance value of the capacitor that acted as the destination capacitor directly before by reducing the content of the destination index register by one, and also the charge transfer from the source capacitor C_(i) to a new destination capacitor C_(k) is continued.

The process of redistribution is still controlled by means of the control module CM on the basis of the output signals of both comparators (K1 and K2) until the voltage U_(i) on the source capacitor C_(i) observed by the use of the first comparator K1 equals zero during the period of time when the function of the destination capacitor C_(k) is assigned to the capacitor C₀ having the lowest capacitance value in the array of redistribution, or the voltage U₀ increasing on the capacitor C₀ having the lowest capacitance value in the array of redistribution and observed at the same time by the use of the second comparator K2 equals the reference voltage U_(L). The value one is assigned to the bits in the digital word corresponding to the capacitors in the array of redistribution on which the voltage equal to the reference voltage value U_(L) has been obtained, and the value zero is assigned to the other bits by means of the control module CM.

According to the invention, the apparatus for clockless conversion of a portion of charge to the digital word comprises the array of redistribution A whose control inputs are connected to control outputs of the control module CM. The control module CM is equipped with the digital output B, the complete conversion output OutR, the gate signal input InG, the first control input In1 connected to the output of the first comparator K1 and the other control input In2 connected to the output of the second comparator K2. The source of auxiliary voltage U_(H), the section of the sampling capacitor A_(n) and the controlled current source J are connected to the array of redistribution A. The control input of the current source J is connected to the output controlling the current source A_(J). The first end of the current source J is connected to the source rail H and the other end of the current source J is connected to the destination rail L. The array of redistribution comprises the sections whose number n equals the number of bits in the digital word.

The section of the sampling capacitor A_(n) and the sections of the array of redistribution A comprise the source on-off switches S_(Hn); S_(Hn-1), S_(Hn-2), . . . , S_(H1), S_(H0), the destination on-off switches S_(Ln); S_(Ln-1), S_(Ln-2), . . . , S_(L1), S_(L0), the ground change-over switches S_(Gn); S_(Gn-1), S_(Gn-2), . . . , S_(G1), S_(G0) and the capacitors C_(n); C_(n-2), . . . , C₁, C₀. The top plates of the capacitors C_(n-1), C_(n-2), . . . , C₁, C₀ of the array of redistribution are connected to the source rail H by the use of the source on-off switches S_(Hn-1), S_(Hn-2), . . . , S_(H1), S_(H0) and to the destination rail L by the use of the destination on-off switches S_(Ln-1), S_(Ln-2), . . . , S_(L1), S_(L0). The bottom plates of these capacitors are connected to ground of the circuit and to the source of auxiliary voltage U_(H) by the use of the ground change-over switches S_(Gn-1), S_(Gn-2), . . . , S_(G1), S_(G0). In the array of redistribution A, a capacitance value of each capacitor C_(n-1), C_(n-2), . . . , C₁, C₀ of a given index is twice as high as a capacitance value of a capacitor of the previous index. The capacitance value of the sampling capacitor C_(n) is twice as high as the capacitance value of the capacitor C_(n) having the highest capacitance value in the array of redistribution. The relevant bit b_(n-1), b_(n-2), . . . , b₁, b₀ in the digital word is assigned to each capacitor C_(n-1), C_(n-2), . . . , C₁, C₀ in the array of redistribution. The destination rail L is connected through the on-off switch of the destination rail S_(Gall) to ground of the circuit and is also connected to the non-inverting input of the second comparator K2 whose inverting input is connected to the source of the reference voltage U_(L). The source rail H is connected to the inverting input of the first comparator K1 whose non-inverting input is connected to the source of auxiliary voltage U_(H). The control inputs of the source on-off switches S_(Hn); S_(Hn-1), S_(Hn-2), . . . , S_(H1), S_(H0) and the control inputs of the on-off switch of the destination rail S_(Gall) are connected appropriately to the control outputs D_(n); D_(n-1), D_(n-2), . . . , D₁, D_(O); D_(all). The control inputs of the destination on-off switches S_(Ln); S_(Ln-1), S_(Ln-2), . . . , S_(L1), S_(L0) and the control inputs of the ground change-over switches S_(Gn); S_(Gn-1), S_(Gn-2), . . . , S_(G1), S_(G0) are coupled together and connected appropriately to the control outputs I_(n); I_(n-1), I_(n-2), . . . , I₁, I₀.

The section of the sampling capacitor A_(n) comprises also the additional sampling capacitor C_(nA), the top plate change-over switches S_(Tn), S_(TnA), the bottom plate change-over switches S_(Bn), S_(BnA) and the input on-off switch S_(Q) connected to the charge input while the control input of the input on-off switch S_(Q) is connected to the output controlling the input on-off switch A_(Q). The capacitance value of the additional sampling capacitor C_(nA) is equal to the capacitance value of the sampling capacitor C_(n). The top plate of the sampling capacitor C_(n) and the top plate of the additional sampling capacitor C_(nA) are connected to the source on-off switch S_(Hn), to the destination on-off switch S_(Ln) and to the input on-off switch S_(Q) through the top plate change-over switches S_(Tn), S_(TnA). The bottom plates of the sampling capacitor C_(n) and the bottom plates of the additional sampling capacitor C_(nA) are connected to the ground change-over switch S_(Gn) and to ground of the circuit through the bottom plate change-over switches S_(Bn), S_(BnA). The control inputs of the top plate change-over switches S_(Tn), S_(TnA) and the control inputs of the bottom plate change-over switches S_(Bn), S_(BnA) are coupled together and connected to the output controlling the change-over switches of plates A_(C). The source on-off switch S_(Hn) is connected to the source rail H, the destination on-off switch S_(Ln) is connected to the destination rail L and the ground change-over switch S_(Gn) is connected to ground of the circuit and to the source of auxiliary voltage U_(H).

In the another exemplary solution, the section of the capacitor C_(n-1) having the highest capacitance value in the array of redistribution comprises the additional capacitor C_(n-1A) having the highest capacitance value in the array of redistribution, the top plate change-over switches S_(Tn-1), S_(Tn-1A) and the bottom plate change-over switches S_(Bn-1), S_(Bn-1A). The capacitance value of the additional capacitor C_(n-1A) having the highest capacitance value in the array of redistribution is equal to the capacitance value of the capacitor C_(n-1) having the highest capacitance value in the array of redistribution. The top plates of the capacitor C_(n-1) having the highest capacitance value in the array of redistribution and the top plates of the additional capacitor C_(n-1A) having the highest capacitance value in the array of redistribution are connected to the source on-off switch S_(Hn-1), to the destination on-off switch S_(Ln-1) and to the input on-off switch S_(Q) by the use of the top plate change-over switches S_(Tn-1), S_(Tn-1A). The bottom plates of the capacitor C_(n-1) having the highest capacitance value in the array of redistribution and the top plates of the additional capacitor C_(n-1A) having the highest capacitance value in the array of redistribution are connected to the ground change-over switch S_(Gn-1) and to ground of the circuit through the bottom plate change-over switches S_(Bn-1) S_(Bn-1A). The control inputs of the top plate change-over switches S_(Tn-1), S_(Tn-1A) and the control inputs of the bottom plate change-over switches S_(Bn-1), S_(Bn-1A) are coupled together and connected to the output controlling the change-over switches of plates A_(C).

The method for conversion of a portion of electric charge to the digital word, according to the invention, is presented in the first exemplary apparatus as follows. Before the first process of conversion of a portion of electric charge to the digital word having the number of bits equal to n, the control module CM introduces the complete conversion output OutR to the inactive state. By the use of the signal from the output controlling the input on-off switch A_(Q), the control module CM causes the opening of the input on-off switch S_(Q) and the disconnection of the charge input InQ from the top plate change-over switches S_(Tn), S_(TnA). The control module CM also causes the switching off the current source J by the use of the signal from the output controlling the current source A_(J). By the use of the signal from the output controlling the change-over switches of plates A_(C), the control module CM causes the switching of the top plate change-over switches S_(Tn), S_(TnA) and of the bottom plate change-over switches S_(Bn), S_(BnA) and the connection of the top plate of the sampling capacitor C_(n) to the source on-off switch S_(Hn) and to the destination on-off switch S_(Ln), the connection of the top plate of the additional sampling capacitor C_(nA) to the input on-off switch S_(U), the connection of the bottom plate of the sampling capacitor C_(n) to the ground change-over switch S_(Gn) and the connection of the bottom plate of the additional sampling capacitor C_(nA) to ground of the circuit.

Next the control module CM introduces the apparatus into the relaxation state shown in FIG. 1. Therefore, the control module CM causes the opening of the source on-off switches S_(Hn-1), S_(Hn-2), . . . , S_(H1), S_(H0) by the use of the signals from the control outputs D_(n-1), D_(n-2), . . . , D₁, D₀. Furthermore, by the use of the signals from the control outputs I_(n); I_(n-1), I_(n-2), . . . , I₁, I₀, the control module CM causes the closure of the destination on-off switches S_(Ln); S_(Ln-1), S_(Ln-2), . . . , S_(L1), S_(L0) and the connection of the top plate of the sampling capacitor C_(n) and the top plates of all the capacitors C_(n-1), C_(n-2), . . . , C₁, C₀ in the array of redistribution to the destination rail L, the switching of the ground change-over switches S_(Gn); S_(G-1), S_(Gn-2), . . . , S_(G1), S_(G0) and the connection of the bottom plate of the sampling capacitor C_(n) and the bottom plates of all the capacitors C_(n-1), C_(n-2), . . . , C₁, C₀ in the array of redistribution to ground of the circuit. By the use of the signal from the control output D_(all), the control module CM causes the closure of the destination rail on-off switch S_(Gall) and the connection of the destination rail L to ground of the circuit enforcing a complete discharge of the sampling capacitor C_(n) and of all the capacitors C_(n-1), C_(n-2), . . . , C₁, C₀ in the array of redistribution. At the same time, by the use of signal from the control output D_(n), the control module CM causes the closure of the source on-off switch S_(Hn) and the connection of the source rail H to the destination rail L and to ground of the circuit which prevents the occurrence of a random potential on the source rail H.

As soon as the beginning of the gate signal G_(x) is detected on the gate signal input InG by the module CM, the apparatus is introduced into the state shown in FIG. 2 by the use of the module CM. Therefore, by the use of the signal from the output controlling the change-over switches of plates A_(C), the control module CM causes the switching of the top plate change-over switches S_(Tn), S_(TnA) and switching of the bottom plate change-over switches S_(Bn), S_(BnA) and the connection of the top plate of the sampling capacitor C_(n) to the input on-off switch S_(Q), the connection of the top plate of the additional sampling capacitor C_(nA) to the source on-off switch S_(Hn) and to the destination on-off switch S_(Ln), the connection of the bottom plate of the sampling capacitor C_(n) to ground of the circuit and the connection of the bottom plate of the additional sampling capacitor C_(nA) to the ground change-over switch S_(Gn) enforcing a complete discharge of the additional sampling capacitor C_(nA). Then, the control module CM causes the closure of the input on-off switch S_(Q) and the connection of the charge input InQ to the top plate change-over switches S_(Tn), S_(TnA) by the use of the signal from the output controlling the input on-off switch A_(Q). The charge delivered to the charge input InQ is accumulated in the sampling capacitor C_(n) which as the only capacitor is then connected to the charge input InQ in parallel through the top plate change-over switch S_(Tn) and through the input on-off switch S_(Q).

As soon as the end of the gate signal G_(x) is detected by the control module CM on the gate signal input InG, the control module CM by the use of the signal from the control output D_(am) causes the opening of the destination rail on-off switch S_(Gall) and the disconnection of the destination rail L from ground of the circuit. By the use of the signals from control outputs I_(n); I_(n-2), . . . , I₁, I₀, the control module CM causes the opening of the destination on-off switches S_(Ln); S_(Ln-2), . . . , S_(L1), S_(L0) and the disconnection of the top plates of the additional sampling capacitor C_(nA) and of the capacitors C_(n-2), . . . , C₁, C₀ in the array of redistribution from the destination rail L, the switching of the ground change-over switches S_(Gn); S_(Gn-2), . . . , S_(G1), S_(G0) and the connection of the bottom plates of the additional sampling capacitor C_(nA) and of the capacitors C_(n-2), . . . , C₁, C₀ in the array of redistribution to the source of auxiliary voltage U_(H). By the use of the signal from the output controlling the change-over switches of plates A_(C), the control module CM causes the switching of the top plate change-over switches S_(Tn), S_(TnA) and of the bottom plate change-over switches S_(Bn), S_(BnA) and the connection of the top plate of the sampling capacitor C_(n) to the source on-off switch S_(Hn) and to the destination on-off switch S_(Ln), the connection of the top plate of the additional sampling capacitor C_(nA) to the input on-off switch S_(Q), the connection of the bottom plate of the sampling capacitor C_(n) to the ground change-over switch S_(Gn) and the connection of the bottom plate of the additional sampling capacitor C_(nA) to ground of the circuit.

If the end of the gate signal G_(x) detected by the control module CM does not constitute the beginning of the next gate signal G_(x+1) as it is shown in FIG. 3, the control module CM causes the opening of the input on-off switch S_(Q) and the disconnection of the charge input InQ from the top plate change-over switches S_(T), S_(TnA) by the use of the signal from the output controlling the input on-off switch A_(Q). The abovementioned state of the apparatus is shown in FIG. 5. As soon as the beginning of the next gate signal G_(x+1) is detected by the control module CM on the gate signal input InG, the control module CM by the use of the signal from the output controlling the input on-off switch A_(Q) causes again the closure of the input on-off switch S_(Q) and the connection of the charge input InQ to the top plate change-over switches S_(Tn), S_(TnA). The charge delivered to the charge input InQ is accumulated in the additional sampling capacitor C_(nA) which as the only capacitor is then connected to the charge input InQ through the top plate change-over switch S_(TnA) and the input on-off switch S_(Q).

If the end of the gate signal G_(k) detected by the control module CM determines simultaneously the beginning of the next gate signal G_(k+1) as it is shown in FIG. 4, the charge is accumulated in the additional sampling capacitor C_(nA) which as the only capacitor is then connected to the charge input InQ through the top plate change-over switch S_(TnA) and the input on-off switch S_(Q). The abovementioned state of the apparatus is shown in FIG. 6.

In both cases, the control module CM introduces the complete conversion output OutR into the inactive state and assigns the initial value zero to all the bits b_(n-1), b_(n-2), . . . , b₁, b₀ in the digital word. Then, the control module CM assigns the function of the source capacitor C_(i) to the sampling capacitor C_(n) by writing the value of the index of the sampling capacitor to the source index register. Simultaneously, the control module CM assigns the function of the destination capacitor C_(k) to the capacitor C_(n-1) having the highest capacitance value in the array of redistribution by writing the value of the index of the capacitor having the highest capacitance value in the array of redistribution to the destination index register. Next, the control module CM starts to realize the process of redistribution of the accumulated electric charge. Therefore, the control module CM by the use of the signal from the output controlling current source A_(J) causes the switching on the current source J. The charge accumulated in the source capacitor C_(i) is transferred to the destination capacitor C_(k) by the use of the current source J though the source rail H and the destination rail L and the voltage U_(i) on the source capacitor gradually decreases and at the same time the voltage U_(k) on the destination capacitor gradually increases during the charge transfer.

In case when the voltage U_(k) on the current destination capacitor C_(k) reaches the reference voltage U_(L) value, then the value one is assigned by the control module CM to the appropriate bit b_(k) in the digital word on the basis of the output signal of the second comparator K2. By the use of the signal from the control output I_(k), the control module CM causes the opening of the destination on-off switch S_(Lk) and the disconnection of the top plate of the destination capacitor C_(k) from the destination rail L, the simultaneous switching of the ground change-over switch S_(Gk) and the connection of the bottom plate of the destination capacitor C_(k) to the source of auxiliary voltage U_(H). Next, the control module CM assigns the function of the destination capacitor C_(k) to the subsequent capacitor in the array of redistribution A whose capacitance value is twice lower than the capacitance value of the capacitor that acted as the destination comparator C_(k) directly before by reducing the content of the destination index register by one. By the use of the signal from the control output I_(k), the control module CM causes the closure of the destination on-off switch S_(Lk) and the connection of the top plate of a new destination capacitor C_(k) to the destination rail L, the simultaneous switching of the ground change-over switch S_(Gk) and the connection of the bottom plate of the destination capacitor C_(k) to ground of the circuit.

In case when the voltage U_(i) on the source capacitor reaches the value zero during charge transfer, then on the basis of the output signal of the first comparator K1 the control module CM by the use of the signal from the control output D_(i) causes the opening of the source on-off switch S_(Hi) and the disconnection of the top plate of the source capacitor C_(i) from the source rail H. By the use of the signal from the control output I_(k), the control module CM causes the opening of the destination on-off switch S_(Lk) and the disconnection of the top plate of the destination capacitor C_(k) from the destination rail L, the simultaneous switching of the ground change-over switch S_(Gk) and the connection of the bottom plate of the destination capacitor C_(k) to the source of auxiliary voltage U_(H). Next, the function of the source capacitor C_(i) is assigned by the control module CM to the capacitor that acted as the destination capacitor C_(k) directly before by writing the current content of the destination index register to the source index register. The control module CM by the use of the signal from the control output D_(i) causes the closure of the source on-off switch S_(H), and the connection of the top plate of a new source capacitor C_(i) to the source rail H. Then, the control module CM reduces the content of the destination index register by one and assigns the function of the destination capacitor C_(k) to the next capacitor in the array of redistribution A having a capacitance value twice lower than the capacitance value of the capacitor that acted as the destination capacitor C_(k) directly before. By the use of the signal from the control output I_(k), the control module CM causes the closure of the destination on-off switch S_(Lk) and the connection of the top plate of a new destination capacitor C_(k) to the destination rail L, the simultaneous switching of the ground change-over switch S_(Gk) and the connection of the bottom plate of a new destination capacitor C_(k) to ground of the circuit. FIG. 7 presents the apparatus in the abovementioned state.

In both abovementioned cases, the control module CM continues the process of electric charge redistribution on the basis of the output signals of the first comparator K1 and of the second comparator K2. Each occurrence of the active state on the output of the second comparator K2 causes the assignment of the function of the destination capacitor C_(k) to the subsequent capacitor in the array of redistribution A whose capacitance value is twice as lower as the capacitance value of the capacitor which acted as the destination capacitor C_(k) directly before. On the other hand, each occurrence of the active state on the output of first comparator K1 causes the assignment of the function of the source capacitor C_(i) to the capacitor in the array of redistribution A that until now has acted as the destination capacitor C_(k), and at the same time the assignment of the function of the destination capacitor C_(k) to the subsequent capacitor in the array A whose capacitance value is twice as lower as the capacitance value of the capacitor which acted as the destination capacitor directly before. The process of redistribution is terminated when the capacitor C₀ having the lowest capacitance value in the array of redistribution A stops to act as the destination capacitor C_(k). Such situation occurs when the active state appears on the output of the first comparator K1 or on the output of the second comparator K2 during charge transfer to the capacitor C₀ having the lowest capacitance value in the array of redistribution A. When the active state appears on the output of the second comparator K2, the control module CM assigns the value one to the bit b₀.

After termination of redistribution of charge accumulated previously in the sampling capacitor C_(n) and after assigning the corresponding values to the bits b_(n-1), b_(n-2), . . . , b₁, b₀ in the output digital word, the control module CM activates the signal provided on the complete conversion signal output OutR. By the use of the signal from the output controlling the current source A_(J), the control module CM causes the switching off the current source J. Next, the control module CM introduces the apparatus into the relaxation phase.

After detecting the end of the next gate signal G_(k+1) by the control module CM on the gate signal input InG, the control module CM by the use of the signal from the control output D_(all) causes the opening of the destination rail on-off switch S_(Gall) and the disconnection of the destination rail L from ground of the circuit. The control module CM by the use of signals from the control outputs I_(n); I_(n-2), . . . , I₁, I₀ causes the opening of the destination on-off switches S_(Ln); S_(Ln-2), . . . , S_(L1), S_(L0) and the disconnection of the top plates of the sampling capacitor C_(n) and of the capacitors C_(n-2), . . . , C₁, C₀ in the array of redistribution from the destination rail L, the switching of the ground change-over switches S_(Gn); S_(Gn-2), . . . , S_(G1), S_(G0) and the connection of the bottom plates of the sampling capacitor C_(n) and of the capacitors C_(n-2), . . . , C₁, C₀ in the array of redistribution to the source of auxiliary voltage U_(H). By the use of the signal from the output controlling change-over switches of plates A_(C), the control module CM causes the switching of the top plate change-over switches S_(Tn), S_(TnA) and of the bottom plate change-over switches S_(Bn), S_(BnA) and the connection of the top plate of the sampling capacitor C_(n) to the input on-off switch S_(Q), the connection of the top plate of the additional sampling capacitor C_(nA) to the source on-off switch S_(Hn) and to the destination on-off switch S_(Ln), the connection of the bottom plate of the sampling capacitor C_(n) to ground of the circuit and the connection of the bottom plate of the additional sampling capacitor C_(nA) to the ground change-over switch S_(Gn).

In case when the end of the next gate signal G_(x+1) detected by the control module CM does not constitute simultaneously the beginning of the subsequent gate signal G_(x+2) as it is shown in FIG. 3, the control module CM by the use of the signal from the output controlling the input on-off switch A_(Q) causes the opening of the input on-off switch S_(Q) and the disconnection of the charge input InQ from the top plate change-over switches S_(Tn), S_(TnA). As soon as the beginning of the subsequent gate signal G_(x+2) is detected by the control module CM on the gate signal input InG, the control module CM by the use of the signal from the output controlling the input on-off switch A_(Q) causes again the closure of the input on-off switch S_(Q) and the connection of the charge input InQ to the top plate change-over switches S_(Tn), S_(TnA). The charge delivered to the charge input InQ is accumulated in the sampling capacitor C_(n) which is then the only capacitor connected to the charge input InQ through the top plate change-over switch S_(Tn) and the input on-off switch S_(Q).

In case when the end of the next gate signal G_(x+1) detected by the control module CM constitutes simultaneously the beginning of the subsequent gate signal G_(x+2) as it is shown in FIG. 4, the electric charge is accumulated in the sampling capacitor C_(n) which is then the only capacitor connected to the charge input InQ through the top plate change-over switch S_(Tn) and the input on-off switch S_(Q).

In both cases, the control module CM deactivates the signal provided on the complete conversion signal output OutR and assigns the initial value zero to all the bits b_(n-1), b_(n-2), . . . , b₁, b₀ in the digital word. Then, the control module CM assigns the function of the source capacitor C_(i) to the additional sampling capacitor C_(nA) by writing the value of the sampling capacitor C_(n) index to the source index register. Simultaneously, the control module CM assigns the function of the destination capacitor C_(k) to the capacitor C_(n-1) having the highest capacitance value in the array of redistribution by writing a value of the index of the capacitor C_(n-1) having the highest capacitance value in the array of redistribution to the destination index register. Next, the control module CM by the use of the signal from the output controlling current source A_(J) causes the switching on the current source J and starts to realize the process of redistribution of charge accumulated in the additional sampling capacitor C_(nA). The process of redistribution is terminated when the capacitor C₀ having the lowest capacitance value in the array of redistribution A stops to act as the destination capacitor C_(k).

After termination of redistribution of charge accumulated previously in the additional sampling capacitor C_(nA) and after assigning the corresponding values to the bits b_(n-1), b_(n-2), . . . , b₁, b₀ in the digital word, the control module CM activates the complete conversion signal output OutR. By the use of the signal from the output controlling the current source A_(J), the control module CM causes the switching off the current source J. Next, the control module CM introduces the apparatus into the relaxation phase.

According to the invention, the method for conversion of a portion of electric charge to the digital word realized in the second exemplary apparatus is as follows. Before the start of the first process of conversion of a portion of electric charge to the digital word having the number of bits equal to n, the control module CM by the use of the signal from the output controlling the change-over switches of plates A_(C) causes additionally the switching of top plate change-over switches S_(Tn-1), S_(Tn-1A) and switching of the bottom plate change-over switches S_(Bn-1), S_(Bn-1A) and the connection of the top plate of the capacitor C_(n-1) having the highest capacitance value in the array of redistribution to the source on-off switch S_(Hn-1) and to the destination on-off switch S_(Ln-1), the connection of the top plate of the additional capacitor C_(n-1A) having the highest capacitance value in the array of redistribution to the input on-off switch S_(Q), the connection of the bottom plate of the capacitor C_(n-1) having the highest capacitance value in the array of redistribution to the ground change-over switch S_(Gn-1) and the connection of the bottom plate of the additional capacitor C_(n-1A) having the highest capacitance value in the array of redistribution to ground of the circuit. FIG. 8 presents the abovementioned state of the apparatus.

As soon as the beginning of the gate signal G_(x) is detected by the control module CM on the gate signal input InG, the control module CM by the use of the signal from the output controlling the change-over switches of plates A_(C) causes additionally the switching of the top plate change-over switches S_(Tn-1), S_(Tn-1A) and switching of the bottom plate change-over switches S_(B-1n), S_(Bn-1A) and the connection of the top plate of the sampling capacitor C_(n-1) having the highest capacitance value in the array of redistribution to the input on-off switch S_(Q), the connection of the top plate of the additional capacitor C_(n-1A) having the highest capacitance value in the array of redistribution to the source on-off switch S_(Hn-1) and to the destination on-off switch S_(Ln-1), the connection of the bottom plate of the sampling capacitor C_(n-1) having the highest capacitance value in the array of redistribution to ground of the circuit and the connection of the bottom plate of the additional capacitor C_(n-1A) having the highest capacitance value in the array of redistribution to the ground change-over switch S_(Gn-1) enforcing a complete discharge of the additional capacitor C_(n-1A) having the highest capacitance value in the array of redistribution. Electric charge delivered to the charge input InQ is accumulated simultaneously in the sampling capacitor C_(n) and in the capacitor C_(n-1) having the highest capacitance value in the array of redistribution which is connected to the sampling capacitor C_(n) in parallel. Both capacitors (C_(n) and C_(n-1)) are the only capacitors that are connected to the charge input InQ through the top plate change-over switches S_(Tn), S_(Tn-1) and the input on-off switch S_(Q). FIG. 9 presents the abovementioned state of the apparatus.

After detecting the end of the gate signal G_(x) by the control module CM on the gate signal input InG, the control module CM by the use of the signal from the output controlling the change-over switches of plates A_(C) causes additionally switching of the top plate change-over switches S_(Tn-1), S_(Tn-1A) and switching of the bottom plate change-over switches S_(Bn-1), S_(Bn-1A) and the connection of the top plate of the capacitor C_(n-1) having the highest capacitance value in the array of redistribution to the source on-off switch S_(Hn-1) and to the destination on-off switch S_(Ln-1), the connection of the top plate of the additional capacitor C_(n-1A) having the highest capacitance value in the array of redistribution to the input on-off switch S_(Q), the connection of the bottom plate of the capacitor C_(n-1) having the highest capacitance value in the array of redistribution to the ground change-over switch S_(Gn) and the connection of the bottom plate of the additional capacitor C_(n-1A) having the highest capacitance value in the array of redistribution to ground of the circuit.

As soon as the beginning of the next gate signal G_(x+1) is detected by the control module CM on the gate signal input InG, the electric charge delivered to the charge input InQ is accumulated simultaneously in the additional sampling capacitor C_(nA) and in the additional capacitor C_(n-1A) having the highest capacitance value in the array of redistribution which is connected to the additional sampling capacitor C_(nA) in parallel. Both capacitors (C_(nA) and C_(n-1A)) are the only capacitors that are connected to the source of converted voltage U_(IN) through the top plate change-over switches S_(TnA), S_(Tn-1A) and the input on-off switch S_(Q).

After detecting the end of the next gate signal G_(x+1) by the control module CM on the gate signal input InG, the control module CM by the use of the signal from the output controlling the change-over switches of plates A_(C) causes the switching of the top plate change-over switches S_(Tn-1), S_(Tn-1A) and switching of the bottom plate change-over switches S_(Bn-1), S_(Bn-1A) and the connection of the top plate of the capacitor C_(n-1) having the highest capacitance value in the array of redistribution to the input on-off switch S_(Q), the connection of the top plate of the additional capacitor C_(n-1A) having the highest capacitance value in the array of redistribution to the source on-off switch S_(Hn-1) and to the destination on-off switch S_(Ln-1), the connection of the bottom plate of the capacitor C_(n-1) having the highest capacitance value in the array of redistribution to ground of the circuit and the connection of the bottom plate of the additional capacitor C_(n-1A) to the ground change-over switch S_(Gn-1).

According to the invention, the another method for conversion of a portion of electric charge to the digital word realized in the exemplary apparatus differs from the previous methods in that as soon as the process of accumulated electric charge redistribution is terminated, the control module CM causes the electric charge, accumulated in the last of capacitors on which the reference voltage U_(L) had not been reached during realization of the process of redistribution, to be conserved.

If the control module CM assigns the value zero to the bit b₀ during the realization of the process of charge redistribution, the control module CM introducing the apparatus into the relaxation state by the use of the signal from the control output I₀ causes the opening of the destination on-off switch S_(L0) and the disconnection of the top plate of the capacitor C₀ having the lowest capacitance value in the array of redistribution from the destination rail L, the switching of the ground change-over switch Seo and the connection of the bottom plate of the capacitor C₀ having the lowest capacitance value in the array of redistribution to the source of auxiliary voltage U_(H).

If the control module CM assigns the value one to the bit b₀ during the realization of the process of redistribution, the control module CM introducing the apparatus into relaxation state by the use of the signal from the control output I_(i) causes the opening the destination on-off switch S_(Li) and the disconnection of the top plate of the source capacitor C_(i) from the destination rail L, the switching of the ground change-over switch S_(Gi) and the connection of the bottom plate of the source capacitor C_(i) to the source of auxiliary voltage U_(H).

Method and Apparatus for Clockless Conversion of Portion of Electric Charge to Digital Word

ABBREVIATIONS

-   A array of redistribution -   A_(n) section of sampling capacitor -   CM control module -   K1 first comparator -   K2 second comparator -   J current source -   U_(H) source of auxiliary voltage -   U_(L) source of the reference voltage -   InG gate signal input -   InQ charge input -   In1 first control input of the control module -   In2 second control input of the control module -   B digital output of the control module -   OutR complete conversion output -   H source rail -   L destination rail -   C_(n) sampling capacitor -   C_(n-1), C_(n-2), . . . , C₁, C₀ capacitors in the array of     redistribution -   C_(n-1) capacitor having the highest capacitance value in the array     of redistribution -   C₀ capacitor having the lowest capacitance value in the array of     redistribution -   C_(nA) additional sampling capacitor -   C_(n-1A) additional capacitor having the highest capacitance value     in the array of redistribution -   C_(i) source capacitor -   C_(k) destination capacitor -   U_(n-1), U_(n-2), . . . , U₁, U₀ voltages on the capacitors in the     array of redistribution -   U_(i) voltage on the source capacitor -   U_(k) voltage on the destination capacitor -   b_(n-1), b_(n-2), . . . , b_(i), . . . , b_(k), . . . , b₁, b₀ bits     in the digital word -   S_(Hn), S_(Hn-1), S_(Hn-2), . . . , S_(Hi), . . . , S_(Hk), . . . ,     S_(H1), S_(H0) source on-off switches -   S_(Ln), S_(Ln-1), S_(Ln-2), . . . , S_(Li), . . . , S_(Lk), . . . ,     S_(L1), S_(L0) destination on-off switches -   S_(Gn), S_(Gn-1), S_(Gn-2), . . . , S_(Gi), . . . , S_(Gk), . . . ,     S_(G1), S_(G0) ground change-over switches -   S_(Tn), S_(Tn-1), S_(TnA), S_(Tn-1A) top plate change-over switches -   S_(Bn), S_(Bn-1), S_(BnA), S_(Bn-1A) bottom plate change-over     switches -   S_(Gall) destination rail on-off switch -   S_(Q) input on-off switch -   A_(C) output controlling change-over switches of the plates -   A_(J) output controlling the current source -   A_(Q) output controlling the input on-off switch -   G_(x) gate signal -   G_(x+1) next gate signal -   G_(x+2) subsequent gate signal -   I_(n), I_(n-1), I_(n-2), . . . , I_(i), . . . , I_(k), . . . , I₁,     I₀ control outputs -   D_(n), D_(n-1), D_(n-2), . . . , D_(i), . . . , D_(k), . . . , D₁,     D₀, D_(all) control outputs 

The invention claimed is:
 1. A method for clockless conversion of portion of electric charge to digital word consisting in accumulation of electric charge delivered to a charge input while the charge is accumulated in a sampling capacitor, or in the sampling capacitor and in a capacitor of the highest capacitance value in an array of redistribution, which is connected in parallel to the sampling capacitor and the charge is accumulated from the instant when a control module detects the beginning of a gate signal to the instant when the control module detects the end of the gate signal, and then consisting in the realization of the process of accumulated electric charge redistribution in the array of redistribution in a known way by means of the control module by changes of states of signals from relevant control outputs, while the array of redistribution comprises an array of on-off switches, of change-over switches and of capacitors such that a capacitance value of each capacitor of a given index is twice as high as a capacitance value of a capacitor of a previous index, and also consisting in the assignment of relevant values to bits of the digital word by means of the control module characterized in that after termination of accumulation of electric charge in the sampling capacitor (C_(n)) or in the sampling capacitor (C_(n)) and in the capacitor (C_(n-1)) having the highest capacitance value in the array of redistribution which is connected to the sampling capacitor (C_(n)) in parallel and after detection of the beginning of the next gate signal (G_(x+1)) by means of the control module (CM), electric charge delivered to the charge input InQ is accumulated in the additional sampling capacitor (C_(nA)), and next the process of redistribution of electric charge accumulated in the additional sampling capacitor (C_(nA)) is realized and relevant values are assigned to bits (b_(n-1), b_(n-2), . . . , b₁, b₀) in the digital word by means of the control module (CM) while accumulation of electric charge in the additional sampling capacitor (C_(nA)) and the process of redistribution of electric charge accumulated in the additional sampling capacitor (C_(nA)) and assignment of relevant values to bits (b_(n-1), b_(n-2), . . . , b₁, b₀) in the digital word are realized such as for the sampling capacitor (C_(n)).
 2. The method for conversion as claimed in claim 1 characterized in that after termination of accumulation of electric charge in the additional sampling capacitor (C_(nA)) and after detection of the beginning of the subsequent gate signal (G_(x+2)) by means of the control module (CM), the next cycle begins and electric charge delivered to the charge input InQ is accumulated again in the sampling capacitor (C_(n)) or in the sampling capacitor (C_(n)) and in the capacitor (C_(n-1)) having the highest capacitance value in the array of redistribution which is connected to the sampling capacitor (C_(n)) in parallel.
 3. The method for conversion as claimed in claim 1 characterized in that in a period of time when electric charge delivered to the charge input InQ is accumulated in the additional sampling capacitor (C_(nA)), a part of electric charge is simultaneously accumulated in the additional capacitor (C_(n-1A)) having the highest capacitance value in the array of redistribution which is connected in parallel to the additional sampling capacitor (C_(nA)) while a capacitance value of the additional capacitor (C_(n-1A)) having the highest capacitance value in the array of redistribution equals the capacitance value of the capacitor (C_(n-1A)) having the highest capacitance value in the array of redistribution.
 4. The method for conversion as claimed in claim 1 characterized in that after termination of process of redistribution, the charge, accumulated in the last of capacitors on which the reference voltage (U_(L)) had not been reached when the process of redistribution was realized, is conserved.
 5. An apparatus for clockless conversion of potion of electric charge to digital word comprising an array of redistribution whose control inputs are connected to control outputs of a control module and the control module is equipped with a digital output, a complete conversion output, a gate signal input, a first control input connected to an output of a first comparator and a second control input connected to an output of a second comparator whereas a source of auxiliary voltage, a section of the sampling capacitor and a controlled current source, whose control input is connected to an output controlling the current source, are connected to the array of redistribution while the first end of current source is connected to a source rail and the other end of the current source is connected to a destination rail whereas the array of redistribution comprises the sections whose number equals the number of bits in the digital word, and the section of the sampling capacitor and each section of the array of redistribution comprises a source on-off switch, a destination on-off switch, a ground change-over switch and at least one capacitor whose top plate is connected to the source rail through the source on-off switch and/or to the destination rail through the destination on-off switch and whose bottom plate is connected to ground of the circuit or to the source of auxiliary voltage through the ground change-over switch while a capacitance value of each capacitor of a given index in the array of redistribution is twice as high as a capacitance value of a capacitor of a previous index, and the destination rail is connected to ground of the circuit through the destination on-off switch and to the non-inverting input of the second comparator whose inverting input is connected to a source of the reference voltage and the source rail is connected to the inverting input of the first comparator whose non-inverting input is connected to the source of auxiliary voltage whereas control inputs of the source on-off switches and a control input of a destination rail on-off switch are connected appropriately to the control outputs of the control module, and control inputs of the destination on-off switches and control inputs of the ground change-over switches are coupled together and connected appropriately to the control outputs of the control module characterized in that the sampling capacitor (A_(n)) comprises the additional sampling capacitor (C_(nA)), the top plate change-over switches (S_(Tn), S_(TnA)), the bottom plate change-over switches (S_(Bn), S_(BnA)) and the input on-off switch (S_(Q)) connected to the charge input (InQ) while the control input of the input on-off switch (S_(Q)) is connected to the output controlling the input on-off switch (A_(Q)) and the top plate of the sampling capacitor (C_(n)) and the top plate of the additional sampling capacitor (C_(n-1)) are connected to the source on-off switch (S_(Hn)) and to the destination on-off switch (S_(Ln)) or to the input on-off switch (S_(Q)) through the top plate change-over switches (S_(Tn), S_(TnA)) whereas the bottom plate of the sampling capacitor (C_(n)) and the bottom plate of the additional sampling capacitor (C_(nA)) are connected to the ground change-over switches (S_(Gn)) or to ground of the circuit through the bottom plate change-over switches (S_(Bn), S_(BnA)) and the control inputs of the top plate change-over switches (S_(Tn), S_(TnA)) and the control inputs of the bottom plate change-over switches (S_(Bn), S_(BnA)) are coupled together and connected appropriately to the output controlling the change-over switches of the plates (A_(c)).
 6. The apparatus for conversion as claimed in claim 5 characterized in that at least one section in the array of redistribution (A) comprises the additional capacitor (C_(n-1A), C_(n-2A), . . . , C_(1A), C_(0A)), the top plate change-over switches (S_(Tn-1), S_(Tn-2), . . . , S_(T1), S_(T0); S_(Tn-1A), S_(Tn-2A), . . . , S_(T1A), S_(T0A)) and the bottom plate change-over switches (S_(Bn-1), S_(Bn-2), . . . , S_(B1), S_(B0); S_(Bn-1A), S_(Bn-2A), . . . , S_(B1A), S_(B0A)) while the top plates of the capacitors (C_(n-1), C_(n-2), . . . , C₁, C₀) and the top plates of the additional capacitors (C_(n-1A), C_(n-2A), . . . , C_(1A), C_(0A)) are connected appropriately to the source on-off switches (S_(Hn-1), S_(Hn-2), . . . , S_(H1), S_(H0)) and to the destination on-off switches (S_(Ln-1), S_(Ln-2), . . . , S_(L1), S_(L0)) or to the input on-off switch (S_(Q)) through the top plate change-over switches (S_(Tn-1), S_(Tn-2), . . . , S_(T1), S_(T0); S_(Tn-1A), S_(Tn-2A), . . . , S_(T1A), S_(T0A)) whereas the bottom plates of the capacitors (C_(n-1A), C_(n-2A), . . . , C₁, C₀) and the bottom plates of the additional capacitors (C_(n-1A), C_(n-2A), . . . , C_(1A), C_(0A)) are connected appropriately to the ground change-over switches (S_(Gn-1), S_(Gn-2), . . . , S_(G1), S_(G0)) or to ground of the circuit through the bottom plate change-over switches (S_(Bn-1), S_(Bn-2), . . . , S_(B1), S_(B0); S_(Bn-1A), S_(Bn-2A), . . . , S_(B1A), S_(B0A)) whereas the control inputs of the top plate change-over switches (S_(Tn-1), S_(Tn-2), . . . , S_(T1), S_(T0); S_(Tn-1A), S_(Tn-2A), . . . , S_(T1A), S_(T0A)) and the control inputs of the bottom plate change-over switches (S_(Bn-1), S_(Bn-2), . . . , S_(B1), S_(B0); S_(Bn-1A), S_(Bn-2A), . . . , S_(B1A), S_(B0A)) are coupled together and connected to the output controlling the change-over switches of the plates (A_(C)).
 7. The apparatus for conversion as claimed in claim 6 characterized in that the capacitance value of the sampling capacitor (C_(n)) and the capacitance value of the additional sampling capacitor (C_(nA)) are not lower than the capacitance value of the capacitor (C_(n-1)) having the highest capacitance value in the array of redistribution.
 8. The apparatus for conversion as claimed in claim 6 characterized in that the capacitance value of the additional capacitor (C_(n-1A), C_(n-2A), . . . , C_(1A), C_(0A)) in the array of redistribution is equal appropriately to the capacitance value of the capacitor (C_(n-1), C_(n-2), . . . , C₁, C₀) in the array of redistribution. 